Hot Hamburger Sandwich - Cooking like a Boss

Traditional Canadian comfort food. It's a burger on top of a slice of bread covered in gravy. Much nicer than it deserves to be! Serve with garden peas and chips.

6 medium onions	dice	fry in burger pan until golden	fry until mushrooms golden	melt	stir in	stir in	season	return burgers to pan	cover and simmer until cooked through	top
oil
12cups 2.84l 2839ml 5pint 189tbsp 568tsp mushrooms	slice
6tbsp 0.09l 90ml 18tsp 0.38cup 0.158pint butter
6tbsp 0.09l 90ml 18tsp 0.38cup 0.158pint flour
1125ml 1 ¹⁄₈l 75tbsp 225tsp 4.76cup 1.98pint beef broth
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint marmite
burgers
1500g 1 ¹⁄₂kg 3.31lb 52.9oz minced beef	mix	form into 12 patties	brown	remove to plate
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint worcestershire sauce
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint garlic powder
salt
pepper
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint onion powder
3 egg
oil
12 slices of white bread